The city walking tour in Salisbury is excellent and at only £6 per person, a bargain for 90 minutes of expert guidance. The tour is limited in size so you won’t find the masses of some free tours as in Bath. History and culture are at the forefront as you walk around central Salisbury and the small group is allowed to go into some building interiors where one sees the transformation of a house and shop from the 15th century to a modern retail store or other business. It ends at the Cathedral, so if you plan accordingly, you are in the right place to tour that splendid site.
My only regret is that we took the tour on our last day of three in Salisbury as we had prioritized time at Stonehenge, Avebury, and Sarum. Might just have to go back as Salisbury is such a pleasing place.